Module 2 · ICU POCUS

🫁 Lung & Pleural Ultrasound

Normal pleura, A-lines and B-lines; pneumothorax, edema/interstitial syndrome, consolidation, pneumonia, atelectasis, pleural effusion and ARDS pattern recognition.

Study time

~70 min

✓Acquire systematic anterior, lateral and posterior lung views appropriate to the clinical question.

✓Recognize normal sliding, A-lines and common vertical artifacts.

✓Use combinations of findings rather than a single sign to assess pneumothorax, edema, consolidation and effusion.

✓Understand why lung ultrasound patterns are sensitive to loss of aeration but often nonspecific for etiology.

Scanning strategy and normal pleura

Start with the pleural line between two ribs and scan enough chest to answer the question.

Use a linear probe for detailed pleural assessment and a curvilinear/phased probe when deeper lung or pleural fluid must be seen.
Normal lung sliding is shimmering movement of the pleural interface caused by apposition of visceral and parietal pleura.
A-lines are horizontal reverberation artifacts deep to the pleura and are commonly seen with normally aerated lung.
A normal scan at one point does not represent the entire hemithorax; scan a protocol appropriate to the clinical problem.

Normal lung sliding
Normal pleural sliding between two rib shadows. Use this as the reference pattern before interpreting absent or reduced sliding.
Contributor: Dr. Matthew Riscinti — Kings County Emergency Medicine
The POCUS Atlas — original media · CC BY-NC 4.0

B-lines and interstitial syndrome

Vertical artifacts reflect reduced aeration near the pleura; distribution and pleural morphology determine meaning.

B-lines are laser-like vertical artifacts that arise at the pleural line, extend to the far field and move with pleural motion.
Diffuse bilateral B-lines with a relatively smooth pleural line can support hydrostatic pulmonary edema in the correct context.
Focal, patchy or asymmetric B-lines occur in pneumonia, contusion, infarction, fibrosis and ARDS; B-lines are therefore not synonymous with cardiogenic edema.
Trend studies using the same protocol and settings when monitoring change over time.

B-lines in pulmonary edema
Vertical artifacts arising from the pleural line. B-lines indicate loss of aeration/interstitial syndrome and must be interpreted in clinical context; they are not specific for cardiogenic edema.
Contributor: Dr. Justin Bowra et al.
The POCUS Atlas — original media · CC BY-NC 4.0

Pneumothorax

Use a hierarchy of signs rather than absent sliding alone.

Absence of lung sliding is sensitive in the right setting but nonspecific: apnea, mainstem intubation, pleurodesis, adhesions and severe parenchymal disease can reduce sliding.
B-lines arising from the pleural line argue strongly against pneumothorax at that exact point because they require apposition of visceral and parietal pleura.
A lung pulse also argues against pneumothorax at the scanned point.
The lung point is highly specific when present, but may not be found in a very large pneumothorax and can be confused with other pleural transition phenomena.
In a crashing patient with a compatible mechanism and physiology, treatment should not be delayed to chase a complete ultrasound protocol.

Lung point
Transition between sliding and non-sliding pleura. In the appropriate setting this is highly specific for pneumothorax, although it may be absent in a very large pneumothorax.
Contributor: Dimitri Livshits, DO; Jane Belyavskaya, MD; Chris Hanuscin, MD
The POCUS Atlas — original media · CC BY-NC 4.0

Consolidation, pneumonia and atelectasis

Once lung loses air it becomes tissue-like and directly imageable.

Consolidation appears tissue-like or hepatized, often with irregular borders and air bronchograms.
Dynamic air bronchograms support pneumonia because air moves within patent bronchi surrounded by consolidated lung.
Static air bronchograms, volume loss and a regular margin may favor atelectasis, but no isolated sign is perfect.
Combine ultrasound with symptoms, microbiology, radiography/CT when indicated and response to recruitment or suctioning.

Dynamic air bronchograms
Movement of echogenic air within a tissue-like consolidation supports pneumonia over simple resorptive atelectasis, but must be integrated with the full clinical picture.
Contributor: Dr. Trauer
The POCUS Atlas — original media · CC BY-NC 4.0

Pleural effusion

Ultrasound is highly useful for identifying, characterizing and safely accessing pleural fluid.

Simple fluid is usually anechoic; complex, septated or echogenic fluid suggests exudate/hemorrhage but appearance alone cannot establish etiology.
The spine sign above the diaphragm supports pleural fluid because sound traverses fluid and allows visualization of the thoracic spine.
Compressed or atelectatic lung may move within a large effusion.
Before thoracentesis identify diaphragm, liver/spleen, lung, depth of fluid and a safe trajectory.

Pleural effusion with compressed lung
Anechoic pleural fluid with compressed lung. Ultrasound can define depth, complexity, diaphragm position and a safer drainage window.
Contributor: Dimitri Livshits, DO; Jane Belyavskaya, MD; Chris Hanuscin, MD
The POCUS Atlas — original media · CC BY-NC 4.0

ARDS and heterogeneous loss of aeration

ARDS usually produces a patchy, nonuniform lung-ultrasound pattern rather than a single diagnostic sign.

Common patterns include irregular/thickened pleura, nonuniform B-lines, spared areas and subpleural consolidations.
Cardiogenic edema more often produces a relatively symmetric diffuse B-line pattern with a smoother pleural line, but overlap is substantial.
Lung ultrasound can help trend aeration and identify superimposed effusion, consolidation or pneumothorax, but does not replace ARDS clinical diagnostic criteria.

Common pitfalls

Calling every B-line pattern 'pulmonary edema'.
Calling absent sliding 'pneumothorax' without checking for B-lines, lung pulse and lung point.
Using a single anterior view to exclude posterior consolidation or effusion.

Radiology correlation

Compare the bedside ultrasound pattern with corresponding ICU radiography cases.

🩻 CXR Case 005 →🩻 CXR Case 006 →🩻 CXR Case 007 →🩻 CXR Case 008 →

Bedside acquisition checklist

☐ Scan both hemithoraces using a reproducible zone approach.

☐ Assess pleural line: sliding, regularity and focal interruption.

☐ Classify artifacts: A-lines, focal B-lines, diffuse B-lines or confluent artifacts.

☐ Look for tissue-like consolidation and air bronchograms when indicated.

☐ Look for pleural fluid and identify the diaphragm.

☐ For suspected pneumothorax integrate sliding, B-lines, lung pulse and lung point.

Check your interpretation

1. Absent lung sliding is seen after intubation. Is pneumothorax proven? →

Answer: No. Absent sliding is nonspecific. Consider mainstem intubation, apnea and pleural disease; look for B-lines/lung pulse/lung point and integrate bilateral ventilation and clinical physiology.

2. What does a focal cluster of B-lines adjacent to an irregular pleura mean? →

Answer: It indicates focal loss of aeration/interstitial involvement, not necessarily hydrostatic edema. Pneumonia, contusion, infarction and other focal processes are possibilities.

Evidence & sources

Volpicelli G, et al. International evidence-based recommendations for point-of-care lung ultrasound: 2025 focused update. Intensive Care Med. 2026;52:1415-1446. doi:10.1007/s00134-026-08487-2.
Demi L, et al. New International Guidelines and Consensus on the Use of Lung Ultrasound. J Ultrasound Med. 2023;42:309-344. doi:10.1002/jum.16088.
The POCUS Atlas — Pulmonary image archive. Media used under CC BY-NC 4.0 with contributor attribution.

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